Bar screen cleaning device



Dec. 19, 1967 T J.TILLETT ETAL 3,358,837

BAR SCREEN CLEANING DEVICE Filed Oct. 22, 1965 3 Sheets-Sheet 1 FIGI fTHOMAS J. TILLET BEDRICH AUERBACH Q Dec. 19, 1967 J. TILLETT TAL3,358,837

BAR SCREEN CLEANING DEVICE 5 Sheets-Sheet 2 Filed Oct. 22, 1965INVENTORS THOMAS J. TILLET BEDRICH AUERBACH Dec. 19, 1967 T. J. TILLETTETAL 8,

BAR SCREEN CLEANING DEVICE Oct. 22, 3 Sheets-sheet 5 United StatesPatent 3,358,837 BAR SCREEN CLEANING DEVICE Thomas J. Tillett, Ambler,and Bedrich Auerbach, Lansdale, Pa., assignors to Link-Belt Company, acorporation of Illinois Filed Oct. 22, 1965, Ser'. No. 500,757 9 Claims.(Cl. 210159) This invention relates to a cleaning device for use inclearing screens employed in the removal of large coarse solid materialsfrom a flowing body of liquid.

In many industrial applications such as that encountered in connectionwith handling sewage and industrial wastes, it is necessary to removedebris and refuse from a flowing stream of liquid. In sewage treatingoperations, for example, it is desirable to remove the solid debris andrefuse from a stream of sewage as it is passing to a settling tank. Theremoval of such debris and refuse from a flowing stream of liquid isgenerally accomplished by the use of an inclined screen made up ofparallel upstanding bars placed in a conduit or channel through whichthe stream of liquid flows. Where the liquid is heavily laden withdebris and refuse, it is necessary to clean the screen at frequentintervals. In order to accomplish this screen cleaning or clearing in aneffective and economical manner, automatic screen cleaning devices arecommonly employed.

A major problem which has been encountered in the use of such automaticscreen cleaning devices has been to provide effective dumping of thedebris and refuse collected from the bar screen by the cleaning deviceinto a discharge outlet. Many of the prior art screen cleaning deviceshave been beset by the disadvantage of being relatively complex andcumbersome, often requiring substantial head room above the liquid flowstream. Other prior art device have not proved satisfactory in that theyhave required relatively close supervision and substantial maintenance.

To overcome the disadvantages of the prior art, it is an object of thepresent invention to provide an improved bar screen cleaning deviceautomatically movable along a guide track which is curved at the upperportion thereof to overlie a discharge outlet in order to achieveeffective dumping of the debris collected by the cleaning device.

Another object of the invention is to provide such a screen cleaningdevice having a raking assembly movable along a guide track which isheld between each debris collecting operation in an at rest openposition and automatically started on its descending movement along thecurved portion of the guide track by spring biased pusher arms.

A further object of the invention is to provide an improved screencleaning device having cooperating guide and pin means for maintaining acleaning rake in a closed position until it is properyl disposed abovethe discharge outlet and means are provided to return the cleaning raketo an at rest open position.

A still further object of the invention is to provide such a screencleaning device employing automatically releasable latch arms formaintaining the raking assembly in position over the discharge outlet atthe end of the curved portion of the guide track while the rake ismoving to an at rest open position for the next debris cleaningoperation.

Still another object of the invention is to provide an improved screencleaning device employing limit switches for automatically controllingthe movement of the raking assembly along the guide track during thescreen cleaning operation.

A further object of the invention is to provide an improved screencleaning device which is relatively simple and economical inconstruction.

In general the invention relates to a screen cleaning device for use incombination with a debris and refuse collecting bar screen comprising aguide track adjacent to the screen, said track having a generallystraight lower portion and a curved upper portion extending over adischarge point, a rake assembly movable along said track assemblyincluding a rake pivotable into and out of engagement with the screen,means for moving said rake assembly along said track and across saidscreen, pin means mounted adjacent the curved portion of said track,guide means mounted on said rake engageable with said pin means toprevent said rake from pivoting to an open position until it ispositioned over the discharge point, latch means for holding saidassembly while said rake is moving to an at rest open position, andpusher means adjacent the curved portion of said track engageable withsaid rake assembly to initiate descending movement of said rake assemblyalong the curved portion of said track towards the lower portionthereof.

The above and other objects of the instant invention will become morereadily apparent by reference to the accompanying drawings wherein apreferred embodiment is disclosed by way of example, variousmodifications and changes of details thereof being contemplated withinthe scope of the appended claims. The apparatus of the invention isillustrated on the accompanying drawings in which:

FIGURE 1 is a vertical sectional view of a screen cleaning deviceaccording to the invention showing the rake in open position during itsdescending movement along the guide track.

FIGURE 2 is a rear sectional view of the screen cleaning device takenalong line 2-2 of FIGURE 1.

FIGURE 3 is a vertical sectional view of the screen cleaning deviceshowing the cable in slack position and the rake pivoting to closedposition at the bottom end of the guide track.

FIGURE 4 is a vertical sectional view of the screen cleaning deviceshowing the rake in closed position during its ascending movement alongthe guide track.

FIGURE 5 is a vertical sectional view of a portion of the screencleaning device showing the raking assembly as it initially contacts thepusher arms with the rake still in closed position just prior toreaching the discharge point for collected debris.

FIGURE 6 is a view similar to FIGURE 5 showing the raking assembly incontact with the pusher arms and the rake in contact with the wiper overthe discharge point for collected debris.

FIGURE 7 is a view similar to FIGURE 5 showing the raking assembly inits upper end limit position over the discharge point along the guidetrack with the rake pivoting toward open position and the latch barsholding the raking assembly in place at the top of the track during thispivoting to open position.

FIGURE 8 is a view similar to FIGURE 5 showing the raking assembly inits at rest open position in readiness for start of its descendingmovement down the guide track and FIGURE 9 is an enlarged detailperspective view of a portion of the raking assembly.

Illustrated in the drawings is a stream 10 of liquid flowing in thedirection of arrow A on FIGURE 1 within channel or conduit 11. Disposedwithin the channel 11 at an angle of approximately 15 to the vertical isa suitable screen, such as bar screen 12, comprised of a plurality ofequally spaced parallel bars 13, for catching debris or refuse in theflowing stream 10 of liquid.

Situated above the bar screen 12 is a housing, generally indicated bythe numeral 14, which contains the screen cleaning device to bedescribed more fully hereinafter. The screen cleaning device generallycomprises a pair of spaced generally channel shaped guide tracks forguiding the raking assembly 16 along a predetermined path to effectcleaning of the screen and dumping of the refuse so collected into adischarge outlet 17 adjacent the top of housing 14. Each of the tracks15 is comprised of a straight lower portion 18 generally parallel to theinclined screen 12 and a curved upper portion 19. The tracks 15 arecurved rearwardly towards the horizontal at their upper end so that theraking assembly may be effectively carried up and over discharge point17 in order to properly discharge refuse collected from the screen 12.An adjustable stop member 20 is provided at the bottom of each of theguide tracks 15 for stopping raking assembly 16 when it reaches thebottom of the tracks.

The raking assembly 16 includes a carriage comprised of a pair ofsliding blocks 21 adapted for sliding movement within the channelsformed by the tracks 15. Each of the blocks 21 is provided with a coveror extension 22 on the inside of the upper end thereof as best shown inFIGURE 9.

Pivotally attached to the upper portion of each sliding block 21underneath the extension 22 at pivot pin 23 is a rake member 24. Rakemember 24 is comprised of a pair of side arms 25 connected by atransverse bar 26 having a plurality of equally spaced teeth 27 as bestseen in FIGURE 2. The raking teeth 27 are adapted to mesh with theopenings between the spaced bars 13 of inclined screen 12 to effectcleaning of the screen as the rake is drawn upwardly across the screenin a so-called closed position. Disposed on the outer side of each ofthe side arms 25 of rake member 24 is a curved guide bar 28, the purposeof which will be discussed more fully hereinafter.

The raking assembly 16 is moved along the guide tracks 15 by means ofcables 31 wound upon a pair of power driven drums 32. The cables 31 areattached to the raking end of rake member 24 by being connected to thetransverse bar 26 at spaced points along the length of bar 26 andinwardly of side members 25. The cable drums 32 are mounted on a shaft33 situated adjacent the top of housing 14. Motor 34 is operativelyconnected to shaft 33 by suitable drive means such as chain 35 extendingaround a sprocket 36 mounted on shaft 33.

A wiper blade 37 extends between and is attached to the sides of housing14 at a point above the discharge outlet 17 and below the rearwardlycurved portions 19 of tracks 15. Wiper blade 37 functions to clean therake teeth 27 of rake member 24 to discharge debris into the dischargeoutlet 17.

Pivotally attached to the sides of housing 14 at points between theupper curved portions 19 of tracks 15 and discharge outlet 17 are a pairof spring :biased pusher arms 38. The pusher arms 38 are biased to pivotdownwardly by a pair of tension springs 39 attached to the pusher armsand the sides of the housing 14. The pusher arms 38 function to initiatedescending movement of the raking assembly 16 along the curved portionsof the tracks 15 at the start of each screen cleaning operation.

A pair of latch bars 41 are pivotally attached to the sides of housing14 above the guide tracks 15 adjacent the top of the housing. One of thelatch bars 41 is provided with an upwardly extending bar 42 Which isadapted to contact and actuate a limit switch 43 mounted on theside ofthe housing just above the latch bar. The actuation of limit switch 43stops motor 34, terminating winding on cable drums 32 of cables 31 atthe end of each screen cleaning operation leaving the rake assembly inan at rest position ready for the next cleaning operation.Alternatively, switch 43 may be connected to recycle the cleaning deviceby reversing the direction of motor 34, starting unwinding of cable fromdrums 32 and permitting the raking assembly 16 to descend to the :bottomof the guide tracks 15. Where switch 43 stops the cleaning device thenext screen cleaning operation may be initiated by a manual pushbuttonor a timer adjusted for periods of 3 to 120 minutes between cycles. Witheither the pushbut- 4 ton or timer the device will be restarted tounwind cable and lower the raking assembly 16.

Also attached to one side of housing 14 adjacent the top thereof at apoint beneath one of the cable drums 32 is a slack cable limit switchassembly 44 having an arm in contact with one of the cables 31. Limitswitch assembly 44 operates to reverse the motor 34 upon slackening ofthe cables 31 which occurs as the raking assembly 16 comes in contactWith the stops 20 at the bottom of guide tracks 15.

A pair of pins 45 are mounted on the sides of housing 14 immediatelybelow the curved portions of guide tracks 15. Pins 45 are positionedapproximately midway of the curved portions of guide tracks 15. As bestillustrated in FIGURES 5 and 6, the pins 45 engage with guide bars 28 onthe side arms 25 of rake member 24 as raking assembly 16 ascends toeffectively prevent the rake member 24- from pivoting to its openposition until it is properly disposed over discharge outlet 17 and hasdischarged any refuse collected from bar screen 12.

In operation of the present invention, the raking assembly 16 initiallyis at a point near the upper end of guide tracks 15 with the rake member24 in its at rest open position as shown in FIGURE 8. In this positionthe spring biased pusher arms 38 press against the cover portions 22 ofsliding blocks 21 and the wire cables 31 restrain the raking assemblyfrom descending down the guide tracks 15. The rake member 24 is holdinglatch bars 41 up to keep switch 43 closed in the deenergized conditionfor the equipment. Upon the activation of the motor 34 the cable drums32 are rotated to cause the cables 31 to unwind and permit the rakingassembly 16 to descend down the guide tracks 15. Start of the rakingassembly along the curved portions 19 of tracks 15 is initiated by theaction of the spring biased pusher arms 38. After the raking assemblymoves around the more nearly horizontal segments of curved portions 19,it contmues its descent down the steeply inclined straight portion ofthe track guides 15 by gravity. During this downward descent, the cableconnections to the rake member 24 are in front of the rake pivot points23 relative to the position of winding drums 32 as shown in FIGURE 1,thus causing the rake tobe held pivoted in an open position by thetension on cables 31.

As the raking assembly 16 reaches the bottom of the guide tracks 15 thesliding blocks 21 contact the lower stops 20 and thereafter the cables31 go slack by contmued unwinding of cable from drums 32. The slackingof cables 31 permits the rake member 24 to swing from ts open positioninto engagement with the bar screen as is shown occurring in FIGURE 3.The pivotal movement of the rake at the bottom of guide tracks causesthe cable connections to shift to the rear of the rake pivot points 23.T1118 latter shifting of the cable connections causes the rake member tobe maintained in closed position when cables 31 are rewound onto drums32 as the raking assembly ascends the guide tracks 15 to clean screen12. The slacking of cables 31 also operates slack cable limit switchassembly 44 thus causing the motor 34 to reverse and commence windingcables 31 back onto the drums 32. This pulls the rake member 24 againstand up the bar screen 12 with teeth 27 passing between the screen bars13 to eifect cleaning of any debris or refuse collected by the screen.

As the raking assembly 16 ascends and enters the curved portions 19 ofthe guide tracks 15, the extensions 22 of the sliding blocks 21 contactthe pusher arms 38 (see FIGURE 5) and extends them against the force ofthe tension springs 39. Thereby the pusher arms are moved to theirloaded position in readiness to assist initial movement of the rakingassembly 16 in starting its next cleaning operation. As the rakingassembly 16 moves through the curved portion of the guide tracks 15 thepivot points 23 of rake member 24 shift to be disposed forwardly of thepath of cables 31 (see FIGURE 6) so that the pull of the cables tends topivot the rake member to the open position. To prevent premature openingof rake member 24, the guide bars 28 on side arms 25 of rake member 24contact pins 45. These pins act to prevent the rake from swinging toopen position until it has discharged the debris into the dischargeoutlet 27 as shown in FIGURES and 6. As the rake is held in closedposition by the guide bars 28 and the pins 45, the rake member passesbeneath wiper blade 37 which functions to clean any remaining debrisfrom the teeth 27 of rake member 24.

As the guide bars 28 clear the pins 45, latch bars 41 drop down toengage the ends of slide blocks 21 and hold the raking assembly 16 atits upper limit position (see FIGURE 7). The latch bars 41 serve to holdthe raking assembly 16 at its upper limit position until the rake member24, having cleared the pins 45, under the tension of cables 31 pivotsback to its open position. During this swinging to open position therake member 24 pushes up the latch bars 41 to release the rakingassembly -16 for descending movement. As latch bars 41 are pushedupwardly by the rake member 24, limit switch 43 is actuated by stop 42on one of the latch bars to either recycle or shut oil? the machine.Also raising of latch bars 41 releases them from their hold on rakeassembly 16 whereupon pusher arms 38 move rake assembly 16 slightlyforwardly of the latching ends of latch bars 41 in readiness for thenext screen cleaning operation. In this condition cables 31 are holdingthe rake assembly 16 against being started in its descent by theremaining spring force of springs 39 acting through pusher bars 38against assembly 16.

It is apparent that the screen cleaning device of the present inventionaflFords many advantages over other prior art screen cleaning devices.For example, the curved upper portion of the guide tracks permits therake to be efiectively positioned over the discharge outlet foreffective disposal of any debris or refuse collected by the rake fromthe screen. Moreover, the cooperating pins and guide bars effectivelyprevent the rake from swinging to open position until it is properlydisposed to discharge the refuse through the discharge outlet. Thespring biased pusher arms 38 also provide effective means of initiatingdescending movement of the raking assembly around the curved portion ofthe guide tracks. Thus, the pins, guide bars, spring biased pusher arms,and latch bars effectively cooperate to permit utilization of the curvedguide tracks in order to achieve an etfective dumping or discharge ofdebris collected by the rake.

In addition, the connecting of the cables at the raking end of the rakemember, in conjunction with the curved and inclined guide tracks,permits the pivot points of the rake to be shifted forwardly andbackwardly of the cables so that the rake is held in open positionduring descending movement and in closed position during ascendingmovement.

Although the present invention has been illustrated and described withreference to a specific embodiment, it will be understood that variouschanges and modifications in the arrangement of parts and components maybe made by persons skilled in the art without departing from the spiritor scope of the invention which is defined by the appended claims.

We claim:

1. A screen cleaning device for use in combination with a screen tocatch debris or refuse in a flowing liquid stream comprising:

guide track means adjacent to the screen to be cleaned having agenerally straight lower portion and a curved upper portion extendingover a discharge point,

a rake assembly movable along said track means including a rake memberpivotable into and out of engagement with the screen,

means for moving said rake assembly along said track means and acrossthe screen,

pusher means adjacent the curved portion of said track means engageablewith said rake assembly to initiate descending movement of said rakeassembly along the curved portion of said track means toward the lowerportion thereof,

and latch means operable to retain said rake assembly against saidpusher means incident discharge of debris from said rake member andmovement of said rake member to an at rest open position in readiness tostart another screen cleaning operation.

2. A screen cleaning device as defined in claim 1 wherein said pushermeans comprises spring biased pusher arm means.

3. A screen cleaning device for use in combination with a screen tocatch debris or refuse in a flowing liquid stream comprising:

guide track means adjacent to the screen to be cleaned having agenerally straight lower portion and a curved upper portion extendingover a refuse discharge point,

a rake assembly movable along said track means including a rake memberpivotable between an open position out of engagement with the screen anda closed position to cleaningly cooperate with the screen,

means for moving said rake assembly along said track means and acrossthe screen,

pin means stationarily mounted adjacent the curved portion of said trackmeans,

guide means mounted on said rake member engageable with said pin meansto prevent said rake member from pivoting from said closed position tosaid open position until it is positioned over said discharge point,

and. latch means operable to retain said rake assembly incident pivotalmovement of said rake member from said closed position to an at restopen position in readiness to start another screen cleaning operation.

4. A screen cleaning device as defined in claim 3 wherein said guidemeans comprises a guide bar mounted on the side of said rake means.

5. A screen cleaning device for use in combination with a screen tocatch debris or refuse in a flowing liquid stream comprising:

guide track means adjacent to the screen to be cleaned having agenerally straight lower portion and a curved upper portion extendingover a discharge point,

a rake assembly movable along said track means including a rake memberpivotable between an open position out of engagement with the screen anda closed position to cleaningly cooperate with the screen,

means for moving said rake assembly along said track means and acrossthe screen,

pin means stationan'ly mounted adjacent the curved portion of said trackmeans,

guide means mounted on said rake member engageable with said pin meansto prevent said rake member from pivoting from said closed position tosaid open position until it is positioned over said discharge point,

pusher means adjacent the curved portion of said track means engageablewith said rake assembly to initiate descending movement of said rakeassembly along the curved portion of said track means towards the lowerportion thereof,

and latch means operable to retain said rake assembly against saidpusher means incident discharge of debris from said rake member andpivotal movement of said rake member from said closed position to an atrest position in readiness to start another screen cleaning operation.

6. A screen cleaning device as defined in claim 5 where in said pushermeans comprises a pair of spring biased pusher arms.

7. A screen cleaning device as defined in claim 5 wherein said pin meanscomprises a pair of pins mounted adjacent the curved portion of saidtrack means and said guide means comprises a pair of guide bars mountedon the sides of said rake member.

8. A screen cleaning device for use in combination with a bar screen tocatch debris or refuse in a flowing liquid stream comprising:

a guide track adjacent to the screen having a generally straight lowerportion and a curved lower portion extending over a discharge point,

a rake assembly movable along said track including a rake memberpivotable into and out of engagement with the screen,

a pair of power operated cables connected to said rake member for movingsaid rake assembly along said track and across the screen, said cablesbeing connected to the raking end of said rake member to hold said rakemember out of engagement with the screen during descending movement ofsaid raking assembly and to maintain said rake member in slidingengagement with the screen during ascending movement of said rakingassembly,

pin means stationarily mounted adjacent the curved portion of saidtrack,

guide means mounted on said rake member engageable with said pin meansto prevent said rake member from pivoting from a closed screen cleaningposition to an open position until said rake member is positioned overthe discharge point,

latch means adjacent the curved portion of said track engageable withsaid rake assembly to hold said assembly in position over the dischargepoint at the end of the curved portion of said track during pivotalmovement of said rake member to said open position,

and pusher means adjacent the curved portion of said track engageablewith said rake assembly to initiate descending movement of said rakeassembly along the curved portion of said track towards the lowerportion thereof.

9. A screen cleaning device for use in combination with a bar screen tocatch debris or refuse in a flowing liquid stream comprising:

a guide track adjacent to the screen having a generally straight lowerportion and a curved upper portion extending over a discharge point,

a rake assembly movable along said track including a rake memberpivotable into and out of engagement with the screen,

a pair of power operated cables connected to said rake member for movingsaid rake assembly along said tracks and across said screen, said cablesbeing connected to the raking end of said rake member to hold said rakemember out of engagement with said screen during descending movement ofsaid raking assembly and to maintain said rake member in slidingengagement with said screen during ascending movement of said rakingassembly,

a pair of pins stationarily mounted adjacent the curved portion of saidtrack,

a pair of guide bars mounted on the sides of said rake member engageablewith said pins to prevent said rake member from pivoting to an openposition until it is positioned over the discharge point,

a pair of latch bars adjacent the curved portion of said trackengageable with said rake assembly to hold said assembly in positionover the discharge point at the end of the curved portion of said trackduring pivotal movement of said rake member to said open position,

and a pair of spring biased pusher arms mounted adjacent the curvedportion of said track engageable with said rake assembly to initiatedescending movement of said rake assembly along the curved portion ofsaid track towards the lower portion thereof.

References Cited UNITED STATES PATENTS 1,392,647 10/1921 Jones 2101591,823,823 9/1931 Dundas et al 210159 1,984,891 12/1934 Miick et al210-159 2,186,790 1/1940 Smyer 210--159 3,152,075 10/1964 Gross 210159REUBEN FRIEDMAN, Primary Examiner.

F. MEDLEY, Assistant Examiner.

" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,358,837 December 19, 1967 Thomas J. Tillett et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 36, for "device" read devices line 55, for "properyl"read properly column 5, line 6, for "27" read l7 column 7, line 8, for"lower" read upper Signed and sealed this llth day of February 1969.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Ir.

Commissioner of Patents Attesting Officer

5. A SCREEN CLEANING DEVICE FOR USE IN COMBINATION WITH A SCREEN TOCATCH DEBRIS OR REFUSE IN A FLOWING LIQUID STREAM COMPRISING: GUIDETRACK MEANS ADJACENT TO THE SCREEN TO BE CLEANED HAVING A GENERALLYSTRAIGHT LOWER PORTION AND A CURVED UPPER PORTION EXTENDING OVER ADISCHARGE POINT, A RAKE ASSEMBLY MOVABLE ALONG SAID TRACK MEANSINCLUDING A RAKE MEMBER PIVOTABLE BETWEEN AN OPEN POSITION OUT OFENGAGEMENT WITH THE SCREEN AND A CLOSED POSITION TO CLEANINGLY COOPERATEWITH THE SCREEN, MEANS FOR MOVING SAID RAKE ASSEMBLY ALONG SAID TRACKMEANS AND ACROSS THE SCREEN, PIN MEANS STATIONARILY MOUNTED ADJACENT THECURVED PORTION OF SAID TRACK MEANS, GUIDE MEANS MOUNTED ON SAID RAKEMEMBER ENGAGEABLE WITH SAID PIN MEANS TO PREVENT SAID RAKE MEMBER FROMPIVOTING FROM SAID CLOSED POSITION TO SAID OPEN POSITION UNTIL IT ISPOSITIONED OVER SAID DISCHARGE POINT, PUSHER MEANS ADJACENT THE CURVEDPORTION OF SAID TRACK MEANS ENGAGEABLE WITH SAID RAKE ASSEMBLY TOINITIATE DESCENDING MOVEMENT OF SAID RAKE ASSEMBLY ALONG THE CURVEDPORTION OF SAID TRACK MEANS TOWARDS THE LOWER PORTION THEREOF,